William Denney spent his formative years in Dover, Delaware, and attended the Wesleyan Collegiate Institute. He began his professional career in insurance, working as a general agent and later as a partner in a local agency. During World War I, he served in the U.S. Army, achieving the rank of first lieutenant. Denney's political career started early, serving a term in the Delaware House of Representatives and later as personal secretary to a U.S. senator. He was elected Governor of Delaware in 1920, where he championed education reform through the "School Law of 1921." Post-governorship, he held various state positions, including acting secretary of state and state librarian, and remained active in the Republican Party.

William Denney's political career is marked by an intriguing blend of fiscal centralization and controversial appointments. His advocacy for the "School Law of 1921" demonstrates a commitment to centralized education funding, yet his involvement in the "Dirty Deal" controversy, appointing Josiah O. Wolcott and T. Coleman du Pont, reveals a penchant for high-stakes political maneuvering. Denney's approach to governance appears highly calculated, balancing ideological consistency with strategic risk-taking.